This invention relates to a polymer composition containing low levels of reactive silanes. More particularly, the invention is directed to the use of such silane containing polymers as removable pressure sensitive adhesives.
There are a number of situations where it is desirable to provide an adhesive which has low initial tack and which may be readily peeled off the substrate to which it has been applied. Such adhesives are required for use, for example, on masking tape, on removable labels, on bumper stickers, etc. In such cases, conventionally employed adhesives have either had such low initial tack that the tapes or labels accidently fall off or they have provided bonds which tend to become gradually stronger so that after some hours, days or months, the tapes or labels can no longer be removed without delaminating either the tape or label or the substrate, a problem referred to as adhesion buildup.
Previous attempts to prevent adhesion buildup have often involved the addition of plasticizers to the adhesive composition. This technique has the disadvantage of migration of the plasticizer out of the adhesive causing staining of the porous substrates on which it is coated. Further consequences of this migration include a change in the properties of the adhesive often resulting in loss of removability as well as fading of the image if the migration occurs into substrates which have been printed using thermal imaging techniques. Other methods for insuring removability involve detackifying or externally cross-linking the otherwise tacky pressure sensitive adhesive, a procedure which is sometimes difficult to control and to uniformly reproduce from batch to batch and which often results in insufficient initial adhesion.